Doping of Alkali, Alkaline-Earth, and Transition Metals in Covalent-Organic Frameworks for Enhancing CO₂ Capture by First-Principles Calculations and Molecular Simulations

Abstract

We use the multiscale simulation approach, which combines the first-principles calculations and grand canonical Monte Carlo simulations, to comprehensively study the doping of a series of alkali (Li, Na, and K), alkaline-earth (Be, Mg, and Ca), and transition (Sc and Ti) metals in nanoporous covalent organic frameworks (COFs), and the effects of the doped metals on CO 2 capture. The results indicate that, among all the metals studied, Li, Sc, and Ti can bind with COFs stably, while Be, Mg, and Ca cannot, because the binding of Be, Mg, and Ca with COFs is very weak. Furthermore, Li, Sc, and Ti can improve the uptakes of CO 2 in COFs significantly. However, the binding energy of a CO 2 molecule with Sc and Ti exceeds the lower limit of chemisorptions and, thus, suffers from the difficulty of desorption. By the comparative studies above, it is found that Li is the best surface modifier of COFs for CO 2 capture among all the metals studied. Therefore, we further investigate the uptakes of CO 2 in the Lidoped COFs. Our simulation results show that at 298 K and 1 bar, the excess CO 2 uptakes of the Li-doped COF-102 and COF-105 reach 409 and 344 mg/g, which are about eight and four times those in the nondoped ones, respectively. As the pressure increases to 40 bar, the CO 2 uptakes of the Li-doped COF-102 and COF-105 reach 1349 and 2266 mg/g at 298 K, respectively, which are among the reported highest scores to date. In summary, doping of metals in porous COFs provides an efficient approach for enhancing CO 2 capture.

Simple synthesis of porous melamine-formaldehyde resins by low temperature solvothermal method and its CO2 adsorption properties

“…To mitigate the effect of global warming, many porous materials, such as metal organic frameworks (MOFs) [5][6][7][8][9], porous co-ordination polymers [10,11], porous carbons [12][13][14][15][16], porous organic polymers (POPs) and covalent organic frameworks (COFs) [17][18][19][20], have been investigated for CO 2 storage. In recent years, many amine functionalized or nitrogen-rich porous materials were found to show good CO 2 adsorption properties because of the existence of strong interactions between the nitrogen functionality and CO 2 molecules [21][22][23][24][25][26][27].…”

Metal–Organic Frameworks with Incorporated Carbon Nanotubes: Improving Carbon Dioxide and Methane Storage Capacities by Lithium Doping

“…[9] Motivated by these experimental and theoretical results, we synthesized hybrid MOF materials by using the two modification techniques outlined above, that is, 1) incorporation of CNTs into [Cu 3 (C 9 sites that become available for interaction with other molecules after removal of H 2 O in from Cu 2+ carbonyl complexes, and can also be easily rehydrated without change of the crystalline nature of the material after exposure to air [11] (see Figure S1 in the Supporting Information). Although the btc ligand can not act as an electron receptor for the electron transfer from the naphthalenide radical anion, [7c] the rehydration of the Cu 2+ sites in the framework makes the electron transfer possible because of the strong nucleophilicity of lithium naphthalenide, which is the main reason for selecting this complex.…”

“…[8] Most recently, the multiscale simulations performed by Lan et al indicate that Li is the best surface modifier of COFs for CO 2 capture among a series of metals (Li, Na, K, Be, Mg Ca, Sc and Ti). [9] Furthermore, their simulations show that the excess CO 2 uptakes of the lithium-doped COFs can be enhanced by four to eight times compared to the undoped COFs at 298 K and 1 bar. [9] Motivated by these experimental and theoretical results, we synthesized hybrid MOF materials by using the two modification techniques outlined above, that is, 1) incorporation of CNTs into [Cu 3 (C 9 sites that become available for interaction with other molecules after removal of H 2 O in from Cu 2+ carbonyl complexes, and can also be easily rehydrated without change of the crystalline nature of the material after exposure to air [11] (see Figure S1 in the Supporting Information).…”

Accuracy of density functional theory in the prediction of carbon dioxide adsorbent materials

“…PBE0 and B3LYP), van der Waals DFT (vdW), and MP2 adsorption energy, E ads [16], and geometry optimization calculations. It is worth noticing that anthracene is structurally and chemically analogous to the organic bridging ligands found in metal-and covalentorganic frameworks, -MOF and COF-, thus our model conforms to a good representation of a promising class of CCS materials [7,[17][18][19][20]. We find that standard, hybrid and vdW functionals of DFT dramatically fail at reproducing CO 2 /AEM-C 14 H 10 interactions as evidenced by E ads discrepancies of ∼ 1 − 2 eV found with respect to MP2 calculations.…”